The sensory organs enable us to interact with our surroundings and perceive things outside our body. As fascinating as their function is, as complex and vast seems the topic during medical studies. Despite the large variety of sensory organs, they all follow a few fundamental principles in their structure and function. From the fundamentals to the necessary detailed knowledge of the different sensory perceptions is only a short way.

00:00
the pharynx. Here are two diagrams
representing the structureof the inner ear. On the left-hand side, you
have what we named, the bony labyrinth. It'sthe bony portion of the ear embedded in the
temporal bone. Inside that bony labyrinthis going to be perilymph fluid. And I'll come back
to that diagram in a moment. On the right-handside, you have the membranous labyrinth. And that
membranous labyrinth is filled with endolymph.
00:39
Now, what I want you to do is place that membranous
labyrinth inside the bony labyrinths.
00:46
And that's exactly what the structure, the anatomical
structure of the inner ear looks like.
00:53
Two components, the bony labyrinth filled with
perilymph, and embedded in there, you havethe membranous labyrinth filled with endolymph.
Let's turn back to the bony labyrinth andlet me point out a few anatomical components.
First of all, you have the vestibule in thecenter. You can see the oval window and the
round window. That vestibule contains therecess for the utricle and the saccule. The
utricle and the saccule is one of the anatomicalcomponents of the inner ear that houses the
receptors for movement of the head, linearmovement of the head and the position of the
head. They house the macula, and I'll talkabout those later on in this lecture. On
the left-hand side, you see the semicircularcanals. They are at right angles to each other.
There are three of them there. Those semicircularcanals, as they approach the vestibule, have
a dilated portion we call the ampulla.
02:14
It's in the ampulla that we have special structures
called cristae. And those cristae house thereceptors for turning the head, moving the
head at an angle, and I'll talk about thosealso in this lecture. Now, the
third anatomical component of theinner ear is the cochlea, shown here. The
cochlea is a spiral-shaped organ. It spiralsabout two and three-quarter turns. And down
the centre core of the spiral is a bone calledthe modiolus bone. And right in that bone
is the spiral ganglia. The spiral ganglionhouses the nerve cell bodies, the neurons,
the bipolar neurons that are going to sendfibres to the hair cells in the cochlea and
transmit information back into the centralnervous system that give us the
sensation of sound.
03:26
This is another diagram to explain what I
mentioned in the previous slide. In fact,this shows you the membranous labyrinth and
just a little bit more detail that I'llbriefly summarize here. Focus on label 1 there.
That's the vestibule. It's a vestibuleof the membranous labyrinth, which the membrane
is enclosed or encloses endolymph. You cansee the macula sacculi and the macula utriculi.
And those two maculae contain sensory receptorsfor the position of the head and linear movement.
Two there, labelled, shows you the semicircularcanals, and a little illustration at the top, just
reminding you that this membranous labyrinthis enclosed in the osseous labyrinth
and surrounded by perilymph.
04:30
As I explained, each of those semicircular
canals has a dilation called the ampulla.
04:35
And within each of those ampulla are the crista,
crista ampullaris. They have their receptors thatrespond to the angular movement or tilting
of the head. So there are three of these.
04:55
Three of these and two maculae, and then finally,
the organ of Corti, the cochlea duct createthe six sensory regions of the inner ear. The
organ of Corti is going to be in the cochleaduct within the cochlea, and that's going
to be responsible for sending sensations backto the central nervous system about sound.
Before we move on and look at those sensory

About the Lecture

The lecture Bony and Membranous Labyrinth by Geoffrey Meyer, PhD is from the course Sensory Histology.

Included Quiz Questions

The bony labyrinth is emended in which of the following cranial bones?

Temporal bone.

Ethmoid bone.

Zygomatic bone.

Sphenoid bone.

Palatine bone.

What is present between the bony labyrinth and the membranous labyrinth?

Perilymph.

Endolymph.

Both endolymph and perilymph.

Air space.

Vacuum.

The receptors for turning the head are present in which of the following inner ear structures?

Ampulla.

Utricle.

Saccule.

Cochlear duct.

Oval window.

How many turns does the spiral of the cochlea have anatomical?

2.75.

2.00.

2.25.

2.50.

3.00.

Author of lecture Bony and Membranous Labyrinth

Geoffrey Meyer, PhD

Customer reviews

(1)
5,0 of 5 stars

5 Stars

5

4 Stars

0

3 Stars

0

2 Stars

0

1 Star

0

User Reviews

(1)
5,0 of 5 stars

5 Stars

5

4 Stars

0

3 Stars

0

2 Stars

0

1 Star

0

Subscribe to bookmark your content

Bookmarks will help you organize our more than 2000 medical videos,
and customize your learning experience for more efficiency and better results.

USMLE™ is a joint program of the Federation of State Medical Boards
(FSMB®) and National Board of Medical Examiners (NBME®). MCAT is a registered
trademark of the Association of American Medical Colleges (AAMC).
None of the trademark holders are endorsed by nor affiliated with Lecturio.